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e-CFR data is current as of August 7, 2020

Title 40Chapter ISubchapter CPart 63Subpart NNNNNN → §63.11412

Title 40: Protection of Environment
Subpart NNNNNN—National Emission Standards for Hazardous Air Pollutants for Chemical Manufacturing Area Sources: Chromium Compounds

§63.11412   What definitions apply to this subpart?

Terms used in this subpart are defined in the CAA, in 40 CFR 63.2, and in this section as follows:

Bag leak detection system means a system that is capable of continuously monitoring relative particulate matter (dust loadings) in the exhaust of a baghouse to detect bag leaks and other upset conditions. A bag leak detection system includes, but is not limited to, an instrument that operates on triboelectric, light scattering, light transmittance, or other effect to continuously monitor relative particulate matter loadings.

Chromic acid means chromium trioxide (CrO3). It is produced by the electrolytic reaction or acidification of sodium dichromate.

Chromium compounds manufacturing means any process that uses chromite ore as the basic feedstock to manufacture chromium compounds, primarily sodium dichromate, chromic acid, and chromic oxide.

Chromium compounds manufacturing facility means the collection of processes and equipment at a plant engaged in chromium compounds manufacturing.

Chromite ore means an oxide of chromium and iron (FeCr2O4) that is the primary feedstock for chromium compounds manufacturing.

Chromic oxide means Cr2O3. In the production of chromic oxide, ammonium sulfate and sodium dichromate that have been concentrated by evaporation are mixed and fed to a rotary roasting kiln to produce chromic oxide, sodium sulfate and nitrogen gas.

Roasting means a heating (oxidizing) process where ground chromite ore is mixed with alkaline material (such as soda ash, sodium bicarbonate, and sodium hydroxide) and fed to a rotary kiln where it is heated to about 2,000 F, converting the majority of the chromium in the ore from trivalent to hexavalent chromium.

Sodium chromate means Na2CrO4. It is produced by roasting chromite ore in a rotary kiln.

Sodium dichromate means sodium bichromate or sodium bichromate dihydrate and is known technically as sodium dichromate dihydrate (Na2Cr2O7 2H2O). It is produced by the electrolytic reaction or acidification of sodium chromate.

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